1. Field of Invention
The present invention relates to the field of fabrics for use in architectural fabric structures. In particular, the present invention relates to a high-strength, non-flammable, waterproof, self-cleaning translucent and weather resistant woven fabric for use in manufacturing architectural structures.
2. Description of the Prior Art
Architectural fabrics have been used to make a wide range of structures. For example, large, permanent roofing systems have been constructed of thick, durable fabric held in place under tension. In the past, the architectural fabric structure business has depended to a large extent on fabric made of fiberglass cloth coated with polytetafluoroethylene (e.g. TEFLON). However, Teflon-coated fabric has many disadvantages and limitations. These include the fact that the overall longevity and tensile strength of Teflon-coated fabrics is poor, and such fabrics are generally very rigid and unpliable. As a result, Teflon-coated fabrics are difficult to work with. Further, Teflon-coated fabrics are very opaque, or have very low levels of light translucency. This limits their utility in many architectural structures. Moreover, Teflon-coated fabrics are not as "self-cleaning" as desired in the industry, soil easily, and thus make them aesthetically unattractive after a short period of use.
Some of the above-noted problems are discussed in U.S. Pat. Nos. 4,472,470 and 3,436,366, the disclosures of which are herein incorporated by reference. As noted in the '470 patent, a roofing structure is disclosed, comprising a base fabric material, a base coating and a silicone top coat. However, the transparent membrane fabric described in patent '470 has several critical flaws. One is that the silicone rubber coating burns readily. This problem can be overcome by loading the rubber with inorganic fillers, but this causes the material to lose its transparency. The flammability of the transparent membrane material precludes its use for fabric structures intented to shelter human beings.
The question of transparency concerns more than the rubber itself. The substrate on to which the rubber is coated can block out a significant percentage of the solar radiation incident upon the fabric. For example, when heavy fiberglass cloth (breaking strength greater than 600 pounds per linear inch) is used as a substrate for transparent rubber, solar transmittance is reduced by 70%. Thus even a transparent coating does not assure a transparent membrane. It is a goal of this patent to provide a silicone coated fabric with increased solar transmittance, high strength, and flame retardancy. The combination of these properties in a single fabric represents a significant advance over the prior art. Additionally, it is an object of this patent to provide a methodology for coating said fabric. The methodology incorporated herein is necessary to insure good adhesion of the rubber to the substrate, an issue not previously addressed in the art.